1. Field of the Invention
The present invention relates to a communication apparatus, a communication system, and a communication method.
2. Description of the Related Art
In the related art, a technology has been known that relates to synchronization in a communication system.
For example, disclosed in Japanese Patent Unexamined Publication (translation of PCT application) No. 2003-509973 is a method of synchronizing multiple base stations in a mobile communication network. In this synchronization method, time information is transferred in the multiple base stations over a local area network (LAN), and a clock generator of each base station that receives the time information is adjusted based on a reception point in time and contents of the time information. Furthermore, in the synchronization method, transmission of a functional sequence relating to a radio time frame to each base station is controlled based on a signal of the clock generator.
For example, disclosed in Japanese Patent Unexamined Publication No. 2007-124633 are communication apparatuses that are connected to one another over a wireless LAN and each of which performs synchronization to the time provided by a clock means. The communication apparatus includes time means indicating the time, time detection means, first frame recognition means, and a second frame transmission means. The time detection means receives a specific first frame that is transmitted to the multiple communication apparatuses over the wireless LAN, or detects the transmission of the specific first frame. The first frame recognition means determines a first-frame detection point in time where the first frame is received or the transmission of the first frame is detected, based on a point in time that is indicated by the clock means. The second frame transmission means transmits a second frame including the first-frame detection point in time to an external communication apparatus over the wireless LAN.
Synchronization precision between the multiple communication apparatuses according to the described-above technology in the related art is not sufficiently high.